The UK's dominant services sector expanded at the weakest pace in nearly two and a half years in September, in further evidence that Britain's recovery lost momentum in the third quarter.

Global economic uncertainty stemming from China, emerging markets and unremarkable growth in the eurozone led to "hesitation" among businesses in placing new orders, while the shock slowdown dragged down overall growth, according to Markit.

The Markit/CIPS headline services PMI dropped to 53.3 in September, from a reading of 55.6 in August. While this was still above the 50 level that divides growth from contraction, output was at its lowest since April 2013 and well below economists' forecast for a pick-up in activity to 56.

Economists said the data suggested Britain started the fourth quarter growing at a quarterly pace of just 0.3pc, following an expansion of 0.7pc in the second quarter of 2015 and estimated growth of 0.5pc between July and September.

If the slowdown continues, the expansion in the final quarter will be the weakest since the final three months of 2012, when the economy contracted by 0.1pc.

Chris Williamson, chief economist at Markit, warned that activity was sliding towards territory that would usually prompt the Bank of England to cut rates or launch more quantitative easing to stimulate the economy.

The data pushed down the pound against the dollar and euro, while economists who had predicted a interest rate hike in the first half of 2016 said risks were now "firmly to the downside". Nomura now believes Bank policymakers will delay raising rates from a record low of 0.5pc until May 2016, from a previous forecast of February.

Markets do not believe the Bank will raise rates until the end of 2016.

David Tinsley, an economist at UBS, said the slowdown in services growth was "getting serious". He said: "If this is an accurate reading of the trajectory of the economy, it increasingly appears that UK growth has taken a marked step down."

Markit said the PMI data for the whole economy suggested growth was slowing to a level that would historically demand more stimulus from the Bank of England

In brighter news, Markit said the rate of job creation in the services sector was the strongest since June, taking the run of jobs growth to 33 straight months.

Michael Saunders, chief UK economist at Citi, was more sanguine about the data. He said said the soft patch suggested by the PMIs was consistent with growth of between 0.5pc and 0.6pc, or around 2.1pc on an annual basis. "These surveys suggest that growth remains comfortably positive, but is no better than average.

"Given all this, the [Bank of England minutes and interest rate decision] on Thursday is likely to show a further drift to a softer outlook for both growth and inflation."